They play PS2 games just fine, all PS3 models do.

Noooo… that’s not right at all. If we are talking unmodified hardware. The original models did have something like 99% compatibility, but as the generation moved on, the fat models removed more components to make it cheaper and made PS2 backward compatibility more software driven… until the slim models removed PS2 disc reading completely.

We used to look at the hard drive size to gauge. 20GB & 60GB was full hardware, 80GB was partial software, anything above was a slim and had no PS2 abilities.

PS1 muddies the water because all PS3s can play PS1 game discs.